Example of unmarshalling a function with struct type as argument

[maxsei]

Hey there, not sure if this is much of an issue, but I did run into some sharp edges when trying to unmarshall a function that takes a struct. After some debugging and reading through the source it turns out both the go struct and the dhall fields must be upper case. Would it be okay to include this gist as an example of how to do this? Let me know, thanks.